[142/262] hugetlb: remove unnecessary set_page_count in prep_compound_gigantic_page

Commit Message

Andrew Morton Nov. 5, 2021, 8:42 p.m. UTC

From: Mike Kravetz <[e-mail]>
Subject: hugetlb: remove unnecessary set_page_count in prep_compound_gigantic_page

In commit 7118fc2906e29 ("hugetlb: address ref count racing in
prep_compound_gigantic_page"), page_ref_freeze is used to atomically zero
the ref count of tail pages iff they are 1.  The unconditional call to
set_page_count(0) was left in the code.  This call is after
page_ref_freeze so it is really a noop.

Remove redundant and unnecessary set_page_count call.

Link: https://lkml.kernel.org/r/[e-mail]
Fixes: 7118fc2906e29 ("hugetlb: address ref count racing in prep_compound_gigantic_page")
Signed-off-by: Mike Kravetz <[e-mail]>
Suggested-by: Pasha Tatashin <[e-mail]>
Reviewed-by: Pasha Tatashin <[e-mail]>
Reviewed-by: Matthew Wilcox (Oracle) <[e-mail]>
Reviewed-by: Oscar Salvador <[e-mail]>
Reviewed-by: Muchun Song <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 mm/hugetlb.c |    1 -
 1 file changed, 1 deletion(-)

Patch

--- a/mm/hugetlb.c~hugetlb-remove-unnecessary-set_page_count-in-prep_compound_gigantic_page
+++ a/mm/hugetlb.c
@@ -1792,7 +1792,6 @@  static bool __prep_compound_gigantic_pag
 		} else {
 			VM_BUG_ON_PAGE(page_count(p), p);
 		}
-		set_page_count(p, 0);
 		set_compound_head(p, page);
 	}
 	atomic_set(compound_mapcount_ptr(page), -1);